Photographic colour material



United States Patent This invention relates to a process and a material for the manufacture of photographic colour images and more especially to a process of colour correction utilizing an .integral masking procedure.

It is known that dyes formed by colour-development in subtractive multicolour photographic pictures do not possess the desired absorption spectrum. The cyan dye which should absorb red light and transmit green and blue light, usually absorbs a major proportion of red light as well as a small amount of green and blue light.

The magenta dye which should absorb green light and transmit blue and red light, usually absorbs aconsiderable amount of blue light and a small amount of red light. The yellow dye which should absorb blue light 0 and transmit green and red light is usually satisfactory.

Due to the unwanted side-absorption of the dyes formed by colour development, it is practically impossible to obtain a true photographic reproduction of the original colours.

Masking of the unwanted side-absorption on printing colour negatives is therefore desirable and this is usually done by using colour masks which make that the density o-f'the unwanted absorptions in the unexposed parts is the same as in the exposed parts. Since separate masks are d ifiicult to register with the colour transparency it is desirable that the mask be integral with the colour images.

A process for the production of a colour photographic image wherein the mask is integral with the colour image is described in the US. patent specifications 3,012,884, 3,079,256 and 3,047,385 and in the German patent specification 1,1 19,666.

More particularly in said German patent specification a process is described'for the manufacture of a colourcorrected image in the photographic material comprising a silver halide emulsion layer and a colour coupler (more particularly a colour coupler of the naphthol type) which is reactive with the oxidation product of an aromatic amino developing agent to form by colour-development a primary dye image (more particularly a cyan dye image) which absorbs a major proportion of light in one region of the visible spectrum (more particularly the red light) and undesirably absorbs a minor proportion of light in at least one other region of the. visible spectrum (more particularly the green light), by treating the exposed and colourdeveloped photographic element with an oxidizing solution (more particularly a photographic bleaching bath), in the presence of a 4-a-mino-pyrazolinone-3compound, which after oxidation couples with. the residual colour coupler, whereby a secondary dye image (more particularly a magenta dye image) having a gradation opposite to thatv of said primary dye image, and absorbing light in at least one of said. unwanted minor absorption regions (more particularly the green light) but transmitting substantially all the light in said major absorption region (more particularly the redlight), is. formed.

It is: anobject of the present invention to provide a new integral masking method for forming a colour corrected photographic colour image used for printing.

It is more particularly an object of the present invention toprovide amask image compensating the unwanted absorption of blue and/or green light of the cyan dye Patented Mar. 21, 1967 image. Other objects will appear from the following description and examples.

These objects are accomplished by treating after colour development an image-wise exposed photographic element, comprising at least one silver halide emulsion layer and a colour coupler, which on development by reaction with the oxidation product of an aromatic primary amino developing agent forms a primary dye image which absorbs a major proportion of light in one region of the visible spectrum, and undesirably absorbs a minor proportion of light in at least one other region of the visible spectrum, with an oxidizing solution in the presence of a 3-amino-guanidine compound of the following general formula:

R represents a hydrogen atom, an alkyl radical, a substituted alkyl radical, an aralkyl radical, a substituted aralkyl radical, and aryl radical, a substituted aryl radical, a heterocyclic radical, or a substituted heterocyclic radical, and

R represents a hydrogen atom or an acyl radical, e.g. an

acetyl radical or a benzene sulfonyl radical,

whereby on oxidatively coupling of the said 3-aminoguanidine compound with the residual colour coupler a secondary dye image is formed, which compensates in at least one region of the visible spectrum, the unwanted side absorptions of the primary dye image.

More particularly a method of forming a colour corrected cyan dye image has been found by forming an integral orange to red mask image in a photographic colour material having in a red-sensitized silver halide emulsion' layer, or in a water-permeable non light-sensitive colloid layer adjacent thereto, a colour coupler for cyan of the phenol type, preferably of the naphthol type, comprising image-wise exposing, colour developing with an aromatic primary amino developing agent, and before or after fixing treating said colour material in a sufficiently strong oxidizing solution eg a photographic bleaching bath comprising potassium ferricyanide, in the presence of a 3-amino-guanidine compound as described above, which couples oxidatively with the residual colour coupler for cyan, thus forming a mask image of opposite gradation to the primary dye image compensating the unwanted side-absorptions of the cyan dye image in the blue and at least partly in the green.

According to a preferred embodiment of the present invention the oxidatively coupling compounds, further also called mask-forming compounds, are preferably used in combination with colour couplers for cyan with the following general formula:

o ONI-I wherein:

X represents an oxygen atom, a sulphur atom, a

group or a sulfonyl group, Y represents a hydrogen atom or a halogen atom,

D represents a diffusion inhibiting group eg an aliphatic hydrocarbon radical with 5 to carbon atoms, preferably with 14, 16 or 18 carbon atoms, and

M represents a hydrogen atom, an alkali metal atom or an ammonium group.

Suitable compounds which give good results and which correspond to the above general formula are:

These colour couplers for cyan can be prepared eg a by the condensation of 1-hydroxy-2-naphthoic acid or its derivatives with the suitable aromatic amides according to the process described in the German patent specification 1,121,061.

Suitable mask-forming compounds which may be used in the process according to the invention are those the formulae of which are given in Table I.

The compounds with the Formulae 1 to 6 are not fast to diffusion. The mask-forming compounds which are not fast to diffusion can be applied in one of the processing baths e.g. the developing bath or the bleaching bath. Preferably they are incorporated int-o the photographic emulsion layer as bicarbonate thus being more or less fast to diffusion.

Mask-forming compounds corresponding to the above general formula can also comprise a diffusion fast making group such as a long aliphatic carbon chain. Examples of compounds which are fast to diffusion and which preferably are incorporated in the emulsion layer are given in Table II.

Although the above-mentioned mask-forming compounds are preferably used in combination With colour couplers for cyan, attention is drawn to the fact that these mask-forming compounds also oxidatively couple with colour couplers for magenta of the pyrazolone class with which dyes are obtained whichmainly absorb-in the Wavelength region of 380 mg to 430mg, thus masking in the blue region of the spectrum.

The mask-forming compounds used, in the process according to the present invention are photographically inert and do not cause fog.

As an illustration for the manufacture of mask-forming compounds according to the present invention detailed examples of the preparation of these compounds as well as references to literature are given below.

Preparation 1 l-(o-methoxy phenyl)-3-aminoguanidine hydroiodide is prepared as follows: I

9 g. of N-(o-methoxy phenyl)-thiourea and 10 cm. of methyliodide are refluxed for 5 -min. in cm. of dry acetone.

After distilling off the acetone, dry ether is added to the residue. A solid precipitate of N-(o-methoxy phenyD-S- methyl isothiouronium iodide-is obtained which is sucked off. Melting point: (decomposition).

15.5 g. of the obtained thiouronium iodide in 100 cm. of pyridine is treated for 4 days with 3 cm. of hydrazine hydrate. After distilling off the pyridine, the solid residue is washed with isopropanol and recrystallized from acetonitrile. The obtained l-(o-methoxyphenyl)-3-aminoguanidine hydr-oidide melts at 176 C.

Preparation 2 Compound 6 from Table I: 1-(N-4-acetylsulphanilyl)- 1-methyl-34aminoguanidine is prepared as described by A.

Preparation 3 1-n-hexadecyl-3-aminoguanidine hydroiodide is prepared as follows:

51 g. of dry ammonia thiocyanate and 70 cm. of benzoyl chloride are refluxed for 5 min. in 450 cm. of dry acetone (ref. R. Frank Organic Synthesis 23, 89). The obtained solution containing benzoyl isothiocyanate and 145 g. of n-hex-adecyl amine are refluxed for 15 min. in 2100 cm. of dry acetone. After filtration 600 cm. of water is added to the reaction mixture. The precipitated N-n-hexadecyl-N'-benzoyl thiourea is sucked off and recrystallized from ethanol. Melting point: 63 C.

125 g. of the obtained thiourea compound and 12.5 g. of sodium hydroxide dissolved in 1875 cm. of ethanol are refluxed for 1 h. The reaction mixture is poured into water and the formed precipitate is sucked off and recrystallized from isopropanol.

After further recrystallization from acetonitrile or ethyl acetate the formed N-mhexadecylthiourea melts at C.

75 g. of N-n-hexadecylthiourea and 290 cm. of methyl iodide are refluxed for 3 h. in 750 cm. of acetone. The obtained precipitate is sucked off and Washed with ether. After recrystallization from ethyl acetate N-n-hexadecyl- S-methyl isothiouronium iodide is obtained whichmelts at 87 C.

56 g. of the obtained thiouronium iodide and 6.8 cm. I

. 1 cm. of hydrazine hydrate in 50 ccs. of methanol.

of hydrazine hydrate are refiuxed for 2- h in 280 cm. ofethanol. After cooling the formed precipitate is suckedoff and recrystallized from acetonitrile. The obtained 1-n:-hexadecyl3-aminoguanidine hydroiodide melts at 103 C. (decomposition).

Preparation 4 1-(p-cetyloxyphenyll-3-aminoguanidine is prepared as follows:

A solution of benzoyl isothiocyanate is prepared from 8.5- g. of ammonium thiocyanate and 11.5 cm. of benzoyl chloride in 50 cm. of acetone as described in preparation 3. At the boiling temperature a solution of 16.7 g. of p-cetyloxyaniline in 50 cm. of acetone isdropwise added. After pouring out into water the obtained precipitate of N-(p-cetyloxyphenyl)-N-benzoyl thiourea is sucked off and refluxed for 15 min. in a solution of 8 g. of sodium hydroxide in 70 cm. of water. The saponified product precipitates immediately. The reaction mixture is neutralized and the p-cetyl-oxyphenyl thiourea is sucked off. After recrystallizing' from benzene the product melts at 129 C.

3292' g. of the obtained thiourea are refluxed with 10 cm? of methyl iodide in 40 cm? of dry acetone for 1 h. After cooling the formed N (p-cetyloxy-phenyl)-S-methyl isothiouronium iodide is sucked off and washed with a little dry ether. Melting point: 116 C.

1.6 g. of the obtained thiouronium iodide are allowed to react at room temperature in cm. of pyridine, for 3 days with 0.5 cm. of hydrazine hydrate. When pouring out intoice the formed l-(p-cetyloxy phenyl)-3-aminoguanidine precipitates. After sucking off and recrystallizing from acetonitrile the aminoguanidine melts at 90 C.

Preparation 5 l -(p-cetylsulphonyl phenyl)'-3-aminoguanidine is. prepared as follows:

A solution of benzoyl isothiocyanate is prepared from 18.8 g. of ammonium thi'ocyanate and 26.6 cos. of benzoyl chloride in 200 ccs. of acetone as described in preparation 3'. At boiling temperature a solution of 84.6 g. of p-cetylsulphonyl aniline in. 800 ccs. of acetone is added gradually. The reaction is completed by refluxing for still 1 hour. After cooling the reaction mixture and pouring it into water, the formed precipitate of N-(p-cetylsulphonyl. phenyl)-N'-benzoyl thiourea is sucked off. This product is shortly boiled with a solution. of 45 g. of sodium hydroxide in 700' ccs. of water so as to saponify it to p-cetylsulphonyl phenyl thiourea. Thereupon it is washed with water andrecrystallized from ethyleneglyool monomethylether. Yield: 90 g. Melting point: 158 C.

8.4 g. of this p-cetylsulphonyl phenyl thiourea is refluxed for 2 hours with ccs. of methyl iodide in 50 ccs. of dry acetone. After cooling, the precipitated N-(p-cetylsulphonyl phenyl-)-S-methyl isothiouronium iodide is sucked off and washed with dry ether. Yield: 9.6. g. Melting point: 130 C.

5.6 g. of the obtained iodide is' refluxed for 1% h. with Y pouring the reaction mixture into water, l-(p-cetylsulphonyl phenyl)-3-aminoguanidine is obtained which is recrystallized from ethyl acetate. Yield: 4 g. Melting point: near 120 C. (with decomposition).

For carrying out the process according to the present invention, the colour couplers and mask compounds are preferably incorporated into a photographic silver halide emulsion prepared by means. of the colloids usually employed therefor, such as for instance gelatin, polyvinyl alcohol, collodion or other natural or synthetic colloids. The silver halide emulsion is preferably coated on a transparent support consisting of glass, nitrocellulose, cellulose esters such as cellulose triacetate, polyester, polystyrene or another natural or synthetic resin, and forms part of a photographic material with one or more emulsion layers.

A multilayer photographic colour material is usually composed of the following layers which are coated onto a support; a red-sensitive emulsion layer having a colour coupler for cyan, a green-sensitive emulsion layer having a colour coupler for magenta and a blue-sensitive emulsion layer having a colour coupler for yellow. Usually there is a yellow filter composed in most of the cases of a gelatin layer containing dispersed colloidal silver, located between the blue-sensitive emulsion layer and the emulsion layer sensitized to green. It is not only possible to incorporate the colour couplers into the lightsensitive silver halide emulsion layer itself but they can also be incorporated into an adjacent non-light-sensitive colloid layer or into a non-light-sensitive layer which is separated from the light-sensitive emulsion layer by a water-permeable colloid layer.

The back side of the transparent support is usually coated with an antihalation layer.

On preparing the. photographic multilayer colour material according to the present invention the mask-forming compound used in this invention is preferably incorporated into the red-sensitive silver halide emulsion layer containing a colour coupler for'cyanof the naphthol type.

The mask-forming compounds according to the invention can also be used in combination with one. of the mask-forming compounds described inthe German patent specification 1,119,666 wherein is described how magenta coloured mask images, which mainly compensate the undesirbale side-absorption in the green part of the spectrum of a cyan dye image, are obtained by oxidative coupling of a 4-aminopyrazolinone-3 compound corresponding to the following general formula: 1

wherein R represents a lower alkyl group,

R represents a lower alkyl group, an aryl group of the benzene series, or a substituted aryl group of the henzene series, and

R represents a diffusion fast making aliphatic radical comprising a linear chain of at least 5 and at most 20 carbon atoms;

with colour couplers for cyan of the naphthol class. In this way a combination of mask-forming compounds can be chosen whereby the undesirable side-absorptions of the cyan dye image in the blue as well as in the green part of the spectrum are almost completely compensated.

The process for the manufacture of a masked photographic colour image according to the present invention proceeds as follows: a light-sensitive multilayer colour material as described above, comprising in the red-sensitive silver halide emulsion layer a colour coupler for cyan of the naphthol type as well as an oxidatively coupling mask-forming compound used in this invention, is exposed to a colour original. This exposed material is developed in a usual colour-developing bath whereby in the exposed areas of the light-sensitive emulsion layers the silver halide is reduced to silver by means of an aromatic primary amino developing agent the oxidation product of which in its turn couples with the colour coupler which is present in the emulsion layers. A cyan colour image which mainly absorbs the red light but also undesirably absorbs a little blue and green light is hereby obtained in the red-sensitive emulsion layer. The maskforming compound in the red-sensitive layer remains; unaffected during colour-development. The colour-developed material is then before or after fixing brought in an oxidative photographic bleaching bath wherein the metallie silver dissolves and the mask-forming compound oxidatively couples with the colour coupler for cyan which is still available in the unexposed areas of the red-sensitive emulsion layer. In this way an orange to red dye mask image is formed, whereby the difference in absorption in the blue and green between the exposed and unexposed parts, which arises by the side-absorption in the blue and the green of the cyan dye image, is compensated.

It has to be noted that the oxidative coupling of the mask-forming compounds used in the present invention does not take place by the oxidative power of the exposed silver halide nor by the oxidative power of the oxidized colour developing agents.

The oxidative coupling whereby the mask image is formed proceeds with an alkaline oxidizing solution the oxidation power of which is preferably of the same strength as the oxidative power of the normally used photographic bleaching baths.

The following aromatic primary amino-compounds can be used as developers for such material: mono-, diand triaminoaryl compounds, more especially N,N-dialkyl-p-phenylenediamines, such as N,N-die thyl-p-phen-- ylenediamine and N,N-diethyl-Z-methyl-p-phenylene diamine, and derivatives thereof such as N,N-dialkyl-N'- sulphomethylor carboxymethyl-p-phenylenediamine. As useful monoamino-developers should be cited: aminophenols and aminocresols or their halogen derivatives and also the aminonaphthols.

The bleaching bath generally contains potassium bromide, borax, boric acid, magnesium sulphate and especially potassium ferricyanide. These elements are dissolved in precisely determined amounts of water so that a solution with a determined pH value above 7 is obtained.

The following examples illustrate the invention.

EXAMPLE 1 To 500 cm. of a red-sensitized bromoiodide emulsion (2% of iodide) containing mol of silver halide, are added g. of the colour coupler: sodium salt of N-(2'- n-hexadecyl sulphonyl-5'-sulpho)-phenyl 1 hydroxy-Z- naphthoic acid amide dissolved in 7 cm. of 2 N sodium hydroxide and 193 cm? of distilled water. To this emulsion is further added 5 g. of the mask-forming compound 1-hexadecyl-3-aminoguanidine dissolved in 12.5 cm? of N sodium hydroxide and 37.5 cm. of ethylene glycol monomethyl ether. After acidifying with 32.5 cm. of N acetic acid to pH 5.7 and after adding the usual ingredients such as hardeners and wetting agents, distilled water is added to the emulsion up to 1000 cm. This emulsion is coated on a suitable support and dried. After exposure through a grey-wedge with a constant 0.15 the material is developed for 9 min. at C. in

a colour-developing bath with the following composition:

' G. Sodium hexametaphosphate (anhydrous) 2 N,N-diethyl-p-phenylene diamine hydrochloride 3 Sodium sulphite (anhydrous) 4 Sodium carbonate (anhydrous) 57 Hydroxylamine hydrochloride (cryst.) 1.5 Potassium bromide (cryst.) 1

Water to 1000 cm. (pl-1:106).

This material is rinsed for 30 minutes at 18 to 20 C. and fixed for 5 minutes at 20 C. in a fixing bath of the following composition:

G. Sodium thiosulphate (anhydrous) 200 Sodium bisulphite (anhydrous) Potassium alum., 24 aq. 20 Sodium biacetate 20 Boric acid (anhydrous) 7.5 Water to 1000 cm. (pH=4.0).

Next, the material is rinsed again for 10 minutes at 18 to 20 C. and treated for 5 minutes in a bleaching bath of the following composition:

G. Potassium ferricyanide (cryst.) Potassium bromide (cryst.) 25 Borax, 10 aq. 20 Boric acid (cryst.) 5

Water up to 1000 cm. (pH=8.8).

Then the material is rinsed again for 10 minutes at 18 to 20 C. and fixed for 5 minutes at 20 C. in a bath of the following composition:

G. Ethylene diamine tetraacetic acid 1 Sodium thiosulphate (anhydrous) Sodium carbonate (anhydrous) 6 Sodium bicarbonate (anhydrous) 14 Sodium sulphite (anhydrous) 10 Water to 1000 cm. (pH=8.9).

EXAMPLE 2 To /2 kg. of a red-sensitized bromo-iodide emulsion (2% iodide) containing mol of silver halide are added 9 g. of N-(6'-cetylsulphonylphenyl)-1-hydroxy-2-naphthoic acid amide-3-sodium sulfonate dissolved in a mixture of cm. of water and 6.3 cm. of an aqueous solution of sodium hydroxide 2 N, 2 g. of 1,2-dimethyl- 4-amino-5-nonylpyrazolinone-3 dissolved in 20 cm. of ethanol with a little sodium hydroxide and 2.5 g. of

1-hexadecyl-3-aminoguanidine dissolved in 6.25 cm. of a N sodium hydroxide and 18.5 cm. of ethylene glycolmonomethylether. After acidifying with N acetic acid to pH 6 and after adding the usual ingredients such as hardeners and wetting agents, distilled water is added up to 1000 cm. After coating, this emulsion forms part of a multilayer photographic material consisting of the following superposed layers in the indicated sequence: an anti-halation layer, a transparent cellulose triacetate support, a subbing layer, the layer of the above-mentioned red-sensitized emulsion with colour coupler for cyan, a gelatin interlayer, a green-sensitized emulsion layer with colour coupler for magenta, a yellow filter layer, a bluesensitive emulsion layer with colour coupler for yellow and at last a gelatin overcoat as antistress layer.

After exposure through a grey wedge with a constant 0.15 the photographic material is developed and further treated as in Example 1. In the red-sensitized silver halide emulsion layer, besides a cyan dye image, also a magenta and orange colored mask image is formed with a graduation opposed to that of the cyan image, and which compensates the undesired side-absorptions of the cyan dye image in the blue as well as in the green.

What we claim is:

1. A method of forming a colour corrected photographic colour image in a photographic element comprising at least one silver halide emulsion layer and a naphthol colour coupler, for cyan which on development by reaction with the oxidation product of an aromatic primary amino developing agent forms a primary cyan dye image, which absorbs a major proportion of light in one region of the visible spectrum, and undesirably absorbs a minor proportion of light in at least one other reigon of the visible spectrum, which method comprises treating said photographic element, after image-wise exposure and colour development, with an oxidizing solution in the presthe following general formula:

wherein:

R is a member selected from the group consisting of hydrogen, an alkyl radical, an aralkyl radical, an aryl radical and a heterocyclic radical, and R is a member selected from the group consisting of hydrogen and an acyl radical, said method comprising treating said photographic element, after image-wise exposure and colour development, with an oxidizing solution, whereby the colour coupler remaining undeveloped after said colour development reacts with said mask-forming compound to form a secondary dye image absorbing light in at least one such other region of the spectrum and having a gradation opposite to that of the primary dye image but transmitting substantially all of that light absorbed in major proportion by said primary dye image.

2. Method of forming a colour corrected image according to the method of claim 1, wherein the mask-forming compound is incorporated in a water-permeable colloid layer of the photographic element.

3. Method of forming a colour corrected image according to the method of claim 1, wherein the oxidizing solution is a photographic bleaching bath.

4. Method of forming a colour corrected image in a photographic element as in claim 1 wherein said element has superposed silver halide emulsion layers each sensitive to a different region of the visible spectrum, at least one of said layers containing said colour coupler of the naphthol type said layer containing said colour coupler containing also said mask-forming compound.

5. Method according to claim 4, wherein the silver halide emulsion layer of the photographicelement-containing said naphthol colour coupler for cyan is sensitive to red light and said coupler corresponds to the general formula:

X is a member selected from the-group consisting of oxygen, sulfur,

-III-alkyl or sulfonyl,

Y is a member selected from the group consisting of hydrogen and halogen,

D is a group making the colour coupler molecule fast to diffusion, comprising an aliphatic hydrocarbon radical with 5 to carbon atoms, and

M is a member selected from the group consisting of hydrogen, an alkali metal atomand an ammonium group.

6. Method according to claim 1, wherein the oxidizing solution is an alkaline photographic bleaching bath comprising potassium hexacyanoferrate (III).

7. Method according to claim 4, wherein said red sensitized silver halide emulsion layer of the photographic element also contains a 4-amino-pyrazolinone-3 compound corresponding to the following general formula:

R is a lower alkyl group,

R is a member selected from the group consisting of a lower alkyl group, an aryl group of the benzene series, and a substituted aryl group of the benzene series, and

R is a radical rendering said compound fast to diffu sion, comprising an aliphatic, linear, hydrocarbon radical of at least 5 and at most 20 carbon atoms.

8. Photographic multilayer colour material having superposed silver halide emulsion layers sensitive to different regions of the visible spectrum, at least one of said layers containing a naphthol colour coupler for cyan which is reactive with the oxidation product of an aromatic amino developing agent to form by colour development a primary cyan dye image which absorbs a major proportion of light in one region of the visible spectrum, and undesirably absorbs a minor proportion of light in at least one other region of the visible spectrum, and a mask-forming compound corresponding to the following general formula:

R is a member selected from the group consisting of hydrogen, an alkyl radical, an aralkyl radical, an aryl radical, and a heterocyclic radical, and

R is a member selected from the group consisting of hydrogen, and an acyl radical.

9. Photographic multilayer colour material according to claim 8, wherein said silver halide emulsion layer containing a colour coupler for cyan of the naphthol type is sensitive to red light.

10. Photographic multilayer colour material having superposed silver halide emulsion layers sensitive to different regions of the visible spectrum as in claim 9, wherein the napththol colour coupler for cyan-contained in said redsensitive emulsion layer has the formula:

SOsM

wherein:

X is a member selected from the group consisting of oxygen, sulfur,

hydrogen, an alkali metal atom and an ammonium group, and a mask-forming compound of the formula:

1 1 wherein:

R is a member selected from the group consisting of hydrogen, an alkyl radical, an aralkyl radical, an aryl radical and a heterocyclic radical, and

R is a member selected from the group consisting of hydrogen and an acyl group.

11. Photographic multilayer colour material as in claim 9 wherein' said red-sensitive emulsion layer also contains a mask-forming compound of the formula:

lower alkyl group and an aryl group of the benzene series, and

R is a group making the mask-forming compound fast to diffusion and comprising an aliphatic, linear hydrocarbon chain of at least 5 and at most carbon atoms.

12. Photographic multilayer colour material having superposed silver halide emulsion layers sensitive to different regions of the visible spectrum, wherein the red-sensitive emulsion layer contains the sodium salt of N-(2'-n-hexadecyl sulfonyl-S-sulfophenyl)-1-hydroxy-2-naphthoic acid amide and 1 (p-n-hexadecyloxyphenyl)-3-aminoguanidine.

References Cited by the Examiner UNITED STATES PATENTS I 2,704,710 3/1955 Sprung 9673 3,013,879 12/1961 De Ramaix et al. 96-55 3,141,771 7/1964 Bard et al 9655 NORMAN G. 'TORCHIN, Primary Examiner.

J. T. BROWN, Examiner. 

1. A METHOD OF FORMING A COLOUR CORREDTED PHOTOGRAPHIC COLOUR IMAGE IN A PHOTOGRAPHIC ELEMENT COMPRISING AT LEAST ON SILVER HALIDE EMULSION LAYER AND A NAPHTHOL COLOUR COUPLER, FOR CYAN WHICH ON DEVELOPMENT BY REACTION WITH THE OXIDATION PRODUCT FOR AN AROMATIC PRIMARY AMINO DEVELOPING AGENT FORMS A PRIMARY CYAN DYE IMAGE, WHICH ABSORBS A MAJOR PROPORTION OF LIGHT IN ONE REGION OF THE VISIBLE SPECTRUM, AND UNDERSIRABLY ADSORBS A MINOR PROPORTION OF LIGHT IN AT LEAST ONE OTHER REGION OF THE VISIBLE SPECTRUM, WHICH METHOD COMPRISES TREATING SAID PHOTOGRAPHIC ELEMENT, AFTER IMAGE-WISE EXPOSURE AND COLOUR DEVELOPMENT WITH AN OXIDIZING SOLUTION IN THE PRESENCE OF A 3-AMINO-GUANIDINE COMPOUND CORRESPONDING TO THE FOLLOWING GENERAL FORMULA: 